Mufflers



Jan, 5, 1960 R. B. SMITH 2,919,761

MUFFLERS Filed May 13, 1957 2 Sheets-Sheet 1 INVENTOR.

R0 Y B. S M l TH ATTORNEY Jan. 5, 1960 R. B. SMITH 2,919,761

v MUFFLERS Filed May 13, 1957 2 Sheets-Sheet 2 INVENTOR. R0 Y B. S M ITH ATTORNEY United. S a e Pa MUFFLERS Roy; B. Smith, Union Township, Fayette County, Ohio, assignor to Vernon N. Holderman, Worthington, Ohio The invention disclosed in this application relates to exhaust. miifilers for internal combustion engines and is illustrated in ,an embodiment thereof shown in the drawing appended hereto.

In recent years internal combustion engines having increased output power-characteristics have been developed for both automobiles and trucks. These developments .have' in some instances also resulted in higher exhaust temperatures and in increases in volume and changes in frequencies of exhau'stnoise; Concurrently with these technical changes, legal restrictions have been imposed on :both the frequency' and volume of noise which is allow- :able both'on highways and in urban areas.

' In order to reconcile these technical and legal factors it has become necessary to develop better and more effective muffiing devices for use on automotive vehicles.

.Many' devices have been. proposed to reduce this increased automotive exhaust noise to satisfactory and legal- Ily acceptable levels, butall such devices so far developed have the undesirable collateral effect of imposing an objectionable degree'of back pressure on the engine exhaust system which serves'to waste engine power and to reduce the operating efficiency of the engine.

, Objects One-of the objects'of my invention is to provide an automotive muffier capable of more rapid dissipation of heat from exhaust gases. v

A further object of my invention is the provision of a muffler which imposes relatively little back pressure on the engine.) Y

A further object of my invention is to provide a mufiler capable of more effective modulation of exhaust noises.

A further object of my invention is to provide an effective muffier of simplified construction which can be produced at relatively low cost.

Further objects and features of my invention will be apparent from the subjoined specifications and claim when considered together with the accompanying dra ings.

- Drawings Fig. 1 is a view in section of a muffier constructed according to my invention;

Fig. 2 is a view in enlarged section taken along line 2-2 of Fig. 1;

Fig.v 3 is a view in enlarged section taken along line 3-3 of Fig. 1;

Fig. 4 is a view in enlarged section taken along line 4-4; and

Fig. 5 is a view in enlarged section taken along line 5--5 of Fig. 4.

Detailed description Referring now to the drawings, it may be seen that ficeswhichdiffer from those of adjacent baffles. 1t

, 2,919,761 Patented Jan. 5, 1960 2 may also be noted that each baflle is spaced from adjacent baffies or end caps at different linear distances depending upon the position of the bafile in the muffier and upon the size, number and characteristics of the orifices in the baflles and end caps.

Referring in detail to the drawings'it is seen that I have shownin Fig. 1 a mufiler 10 having a cylindrical body portion 11, oppositely disposed substantially hemispherical end caps 12 and 13, an inlet tube 14, an outlet tube 15, and intermediate bafiies 16, 17, 18 and 19 secured to said mufller 10 in the manner and having the configuration which is described hereafter in detail.

Inlet tube 14 has an inside diameter slightly greater than the outside diameter of the exhaust pipe 20 leading either from the exhaust ports or from the exhaust manifold of the engine with which muffier 10 is to be used. Inlet end cap 12 is formed in my preferred embodiment having the substantially hemispherical configuration shown in Fig. 1, although it may also be formed having a circular plane configuration if desired. End cap 12 has a centrally disposed circular opening 21 having an inside diameter substantially equal to that of inlet tube 14. Inlet tube 14 is secured by suitable gas-tight and heat-conducting means to the outer convex surface of end cap 12 with one of its ends in register with opening 21.

Cylindrical body 11 is formed with any length and inside diameter necessary to accommodate the passage of the exhaust gas output of the exhaust pipe 20 of an engine with which the device is to be employed.

Inlet end cap 12 has an outside diameter substantially equal to the outside diameter of cylindrical body 11 and is' secured in gas-tight and heat-conducting peripheral engagement with one end of body 11 so as to extend axially therefrom.

' Outlet end cap 13 is formed with a convex configuration similar to that of cap 12 and has a centrally disposed circular opening 22 having a suitable diameter not less than the diameter of opening 21 of inlet cap 12. Outlet tube 15 has an inside diameter substantially equal to that of opening 22 and is secured in gas-tight and heat-conducting peripheral engagement with end cap 13 so as to be in register with opening 22 and to extend axially from the outer or convex surface of end cap 13.

=-Bafi1e 19 is formed of suitable heat conducting material with the general circular configuration shown in Figs. 4 and 5 with an outer annular flange 23 extending perpendicular to one face 24 of said bafile and having an outside diameter after forming substantially equal to the inside diameter of body 11. Bafile 19 is further formed with a centrally disposed orifice 25 and a plurality of orifices 26 suitably spaced in a plurality of circles lying within the plane of baflle 19 and concentrically spaced from central orifice 25. Orifices 25 and 26 are each circumscribed by annular extrusions 27 which extend substantially perpendicular to forwardly disposed surface 28 of baffle 19.

Bafile 18 is like baflle 16 and is formed to the general circular configuration of Fig. 2 having an outside diameter after forming substantially equal to the inside diameter of body 11, having a forwardly disposed face 38, a centrally disposed orifice 35 with a minimum diameter greater than that of orifices 25 and 26 of bafile 19 and having a plurality of orifices 36 equal in diameter with orifice 35 and spaced concentrically about said orifice 35. Orifices 36 are fewer in number than are orifices 26 of baflie 19 and orifices 35 and 36 are each circumscribed by an annular extruded portion 37 of bafiie 18 formed to a cross-sectional configuration similar to that shown at 27 in Fig. 5 and projecting forwardly from and substantially perpendicularly to the forward face 38 (Fig. 2). Baflle 18 is further formed with a rearwardly extending flange 33 similar to the flange 23 of baflle 19 shown in detail in Fig. 5.

Baflle 17 is formed to the general circular configuration shown in Fig. 3 having an outside diameter after forming substantially equal to the inside diameter of body 11. Baffle .17 has a single centrally disposed orifice 45 with a diameter substantially equal to .the inside diameter of inlet tube 14 (Fig. l). Orifice 45 is further formed with a forwardly projecting extruded peripheral portion 47 circumscribed about said orifice and formed substantially to the crosssectional configuration shown at 27 in Fig. 5. Baflle 17 also has a rearwardly projecting annular flange 43 (Fig. 3) formed substantially as shown at 23 in Fig. 5.

Bafiie 16 is formed to substantially the same general configuration shown as baffle 18 shown in detail in Fig. 2 and described before herein.

Each of said baffles 16, 17, 13 and 19 (Fig. 1) are arranged within body 11 perpendicular to the longitudinal axis of body 11 so as to form successive chambers 51, 52, 53, 54 and 55 within the assembled mufiier 10. Said baffles 16, 17, 18 and 19 are spaced from each other and from outlet end cap 13 by respective linear distances required to define an approximate volumetric relationship between chamber 52, and chambers 53, 54, 55 and 51.

Tests have indicated that baflle 16 should be spaced from baffie 17 a distance not less than one and one-half inches and not greater than two and one-half inches as measured along the longitudinal axis of body 11. Bafile 18 is spaced from baffle 17 sufficiently far to define a chamber 53 having a volume approximately two and one-half times that of chamber 52 formed by the spaced relationship just described between baffies 16 and 17. Baflie 19 isspaced from baflie 18 sufiiciently far to define achamber 54 having a volume approximately one and one-half times that of chamber 52. All bafiles 16, 17;

In operation the exhaust pipe 20 (Fig. 1) of an engine is secured in gas-tight engagement within inlet tube 14 by suitable means such as for instance clamp 39 and outlet tube is secured by similar means 49 inv engagement within a suitable tailpipe 30.

Exhaust gases from the engine (not shown) are introduced under engine pressure and at normal engine ex-- haust. temperature through engine exhaust pipe into chamber 51 where said gases are cooled by conduction as they come .in contact with the walls of chamber 51. Said gases are then urged under engine pressure through orifices 66 of baffie 16 and into chamber 52. In passing the gases through the moderately sized orifices of bafiie 16 the exhaust noise components having intermediate frequency characteristics are modulated to sound From chamber waves of less undesirable frequencies. 52 said exhaust gases are passed substantially under engine pressure through orifice 45 of baffle 17 whereby objectionable high frequency components of exhaust noise are modulated to sound waves of a less objectionable frequency. From chamber 53 the gases are passed through orifices 36 for a second sound modulating effect similar to that produced by orifices 66 of baffle 16 which are similar in size, number and configuration to orifices 36. From orifices 36 the gases pass-into cham-,

ber 54 and then pass through orifices 26 where the exhaust noise components of lower objectionable fre:;

quencies are modulated to frequencies which areless 4' 1 objectionable in character. Thereafter all exhaust gases are ejected through outlet-opening 22, outlet tube 15- and tailpipe 30.

The normal resistance to the flow of a fluid through an orifice in a plane surface is reduced and the rate of flow of exhaust through bafile orifices 66, 45, 36 and '26 is increased over the normal rate by means of the extruded configuration ofeach baffie orifice which is employed in the device as shown in the cross-sectional view of orifices and 26 in Fig. 5. The increase in rate of flow through each baffie orifice which is thus achieved serves to reduce the total back pressure imposed by u r 10 up n he n ne;

By arranging successive bafiles in the sequence shown in Fig. 1 straight line passage of exhaust gases through the muffler is prevented, except for a limited proportion of the total volume of the total gas which is permitted to pass directly along the longitudinal axis of muffier 10 as a further aid in reducing the back pressure of the muffler and is subjected to the successive sound modulating effect of central orifices 65', 45, and 25. substantially as previously described.

The previously described peripheral extruded portions of all baflie orifices such as that shown at 27 in Fig. 5 further serves to expose more total heat conducting surface to contact withthe exhaust gases and therefore serve the additional purpose, of providing increased, cool-- ing facilities for the gases as a further aid in diminishscribed, baffie 18 has seven orifices and,v bafile 19, has.

nineteenorifiees, In mufflers of larger, diameter bafiies corresponding to bafiles16, 18 and 19 may have a greater number of orifices. For instancev in one Inufiler having a greater diameter,,. th e bafile. corresponding tonbaffie 16 as illustrated has nineteen orifices; the, tbafile corresponding to 17 hasgone orifice; the bafile corresponding; to 18 has nineteen orifices; and the bafile corresponding observed and measured by means of a conventionalsound level meter and octave band noise analyzer:

Noise Noise Source of Sound Level in Analysis Decibels in Soncs Engine runninz at full throttle with:

(1) No muffler (2) Conventional type rnufller 91 107,- (3) Improved muflier described herein 89 05 Engine back pressure tests indicated that the effective back pressure on an engine equipped with the muffierdescribed-herein was approximately one-half inch of mercury when the engine was operating at full throttle R.P.M. and under normal load conditions. Comparable tests in which a muffler of conventional design was similarly employed indicate that such mufilers exert back pressuresin the order of two inches of mercury under similar conditions.

Baffles 16, 17, 18 and 19 are secured within body 11 by welding as seen at weld 71 in Fig. 5 although any other suitable heat-conducting means may be employed such as for instance brazing, soldering, riveting, or tight frictional engagement which may be achieved by methods well knownin the art. I prefer to insure satisfactory heat conduction by welding.

The muflier configuration which I have described herein andillustrated in the appended drawings is particularly suited. to: production methods. whereby a, protective coat:

ing such as a coating of metallic or ceramic materials is applied to all interior and exterior surfaces of a mufller after the mufiier is assembled. The unidirectional alignment of all protruding surfaces of bafiies 16, 17, 18 and 19, together with the concave inner configuration of end cap 13 serve to facilitate the rapid drainage of coating material from the interior of the mutller which is essential to such production methods.

It is to be understood that the above described embodiment of my invention is for the purpose of illustration only and various changes may be made therein Without departing from the spirit and scope of my invention.

I claim:

A mufiler comprising a hollow casing having an inlet end and an outlet end; a substantially hemispherical inlet head having an inlet tube at the inlet end; a substantially hemispherical outlet head having an outlet tube at the outlet end; a first transverse baflle secured within said casing adjacent to the inlet end and having a plurality of extruded orifices consisting of a centrally positioned orifice extending therethrough and a plurality of other orifices arranged concentrically with said centrally positioned orifice and extending therethrough, all of said orifices being formed with circular flanges; a second transverse baille having a single extruded orifice extending therethrough and formed with a circular flange and spaced from the first baffle by a distance of from one and a half inches to two and one half inches measured along the longitudinal. axis of the body for defining a first chamber of predetermined volume intermediate said bafiles; a third transverse bafiie substantially similar in configuration with said first bafile and spaced from said second baffie a sufiicient distance to define a second chamber intermediate said second and third baffies, having a volume approximately two and one-half times the volume of said first chamber; a fourth transverse baffle having a plurality of extruded orifices, greater in number than said first baffle, interpositioned between said third bafile and said outlet head for forming a third chamber intermediate said third and fourth baffles having a volume approximately one and one-half times the volume of said first chamber, and for further forming a fourth chamber intermediate said fourth bafile and said outlet head having a volume not greater than twice the volume of said first chamber; all of said bafiles being further spaced from said inlet head a distance sufiicient for defining an intake chamber intermediate said inlet head and said first bafile having a volume not less than twice the volume of said first chamber.

References Cited in the file of this patent UNITED STATES PATENTS 813,203 lFranquist Feb. 20, 1906 1,004,195 Porter Sept. 26, 1911 1,539,595 Powell May 26, 1925 1,756,916 I Stranahan Apr. 29, 1930 1,810,252 Noonan June 16, 1931 1,874,326 Mason Aug. 30, 1932 FOREIGN PATENTS 872,105 France May 30, 1942 177,972 Austria Mar. 25, 1954 

